Money is the main reason why most self-published writers do not hire professional editors and proofreaders. Ninety percent of self-published books have sales of less than one hundred copies in their first year of release - this does not make the hiring of a professional editor a very cost effective option for most self-published authors.
To illustrate this point, let's create a hypothetical self-published author and call her Bertha Hack. Bertha has sold 50 print copies of her 75,000 word novel Vampire Loins on Fire for which she has received a royalty of $4.00 per copy. Her ebook sales are considerably better. It has sold 100 copies and Bertha has received $1.00 for each copy sold. So Bertha's total royalties for her debut novel is a whopping $300.
Now, let's turn to what most editors and proofreaders charge. Amazon's Createspace offers a basic copyediting service for what is considered a very reasonable price. Send your manuscript to Createspace and an editor will check over the manuscript for basic grammar, spelling, and punctuation mistakes. For this service Createspace charges $160.00 for up to 10,000 words or .016 cents per word for anything over 10,000 words. Since Bertha Hack's novel clocks in at 75,000 words, her editing job will set her back $1200.
So, if Bertha had submitted her work to a professional editor, she would still be $900 in the hole for Vampire Loins on Fire. A high price to pay just to appease a few readers who are error-sensitive. Now some might argue that Bertha would have sold far more books if she had hired a pro edit it, but this is pure conjecture. In fact, I think it's utter horseshit. There are too many terribly written and terribly edited self-published bestsellers out there that prove that the quality of editing has very little to do with sales most of the time.
As for me, I plug away at proofreading bit by bit on my own because I cannot at this stage in the game afford to pay for professional editing. My book, The City of Earthly Desire comes in at 230,000 words. Using the Createspace service as a gauge, it would cost me about $3400 to have the text professionally edited. I care about the quality of my work, but I also like to eat and buy my kid diapers.
The good thing about self-publishing and print-on-demand is you can make changes to the text at any time and as many times as you want. I have uploaded two proofread versions of my novel The City of Earthly Desire since its release a year ago. Each version is a little bit better than the one before. I'm hoping this next one I will complete in a week or two will be almost perfect. And even if it isn't, I think I'll be able to digest a criticism or two concerning editing, were they ever to come my way.